The present disclosure relates to semiconductor processing methods, and particularly to methods for patterning a dielectric material layer employing a titanium oxynitride hard mask and structures for effecting the same.
In semiconductor manufacturing, patterning of a dielectric material layer to form via trenches and line trenches is necessary to form metal interconnect structures. Titanium nitride (TiN) hard mask layer consisting of titanium and nitrogen is frequently employed as a hard mask layer during the patterning process.
Unfortunately, removal of a TiN hard mask layer cannot be easily performed without causing collateral damages. Removal of the TiN hard mask layer by a reactive ion etch after formation of a dual damascene cavity causes damages to physically exposed copper surfaces of underlying interconnect structures. Removal of the TiN hard mask layer by a wet etch can also attack the physically exposed copper surfaces of an underlying interconnect structures. Removal of the TiN hard mask layer by a wet etch prior to physically exposing copper surfaces of underlying interconnect structures results in widening of lateral dimensions of via cavities and an increase in the probability of forming physically shorted via structures.